Document US 2003/0095476 describes an apparatus for a waking control system. The apparatus comprises a detection system for measuring a parameter correlated to an individual's sleep level, and a system controller for introducing a stimulus based on this parameter, before a user-settable wake up time. The apparatus is intended to gradually introduce the stimulus, such as light, before the planned wake up time, in order to wake the individual gradually to promote wellness. It is further described to take into account the seasonal amount of light, as determined by the date.
A disadvantage of the known apparatus is that, in practice, it does not always function properly. Sometimes it happens that the user is woken too early, and at other times he is woken too late, or even not at all, at least not by the apparatus.